These half shafts you're using, are they turbo axles or NA ones? Are they breaking because they're from pepboys or autozone?

 

they are t2. You could snap a NA half shaft over you knee its so thin so i would never try and use anything like that. And the replacement t2 ones you order from pepboys seem to work great but face it the RX7 was never built to be a all out drag machine. If you want a drag racer convert the rear end and axle over to a ford 1 piece. If not live with trashing half shafts.